Hi, I've tried your game and while the concept seems interesting, I've found the reason for the "player coop". Let me explain, I really love platformers and the killwall mechanics is very intriguing, allowing a player to master the perfect coordination of jumping timing, enemy evading etc.. but there's no cooperation between players, no interaction, no different skill/abilities.
The players just need to stick together and perform the same movement.
My suggestion is to add interaction between players, this can be done in various ways:
- Player 1 have an axe and can kill enemies, Player 2 jump higher and can trigger environment to help other
- Allow the players could teleport on each other, this would allow some kind of funny tricks, like teleporting on falling etc.
- Players have different kind of "resistance" and can stand on each other
You could also mix few of these ideas together and see what works.
Anyway go on on your work